Two-temperature evaporator



R. s. TA/YLOR March 7, 1933.

TWO-TEMPERATURE EVAPORATOR Filed Feb. 7, 1931 INVE' TOR.

08 6 ATTORNEY Patented Mar. 7, f33

outrun iterate ROBERT S. TAYLOR, OF EVANSWI'LLE, INDIANA, ASSIGNOB TO ELECTROLUX SEVEL CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE TWO-TEMPERATURE EVAEORA'IOR Application filed February 7, 1931. Serial No. 514,154.

This invention relates to refrigerating apparatus of the absorption type, and more particularly to an evaporator or cooling element for use in absorption refrigerating system of the continuous type in which circulates an inert gas or other pressure equalizing medium.

In refrigerators both of the household. and commercial types a low temperature is usually required for freezing water, desserts, and the like, and a higher temperature for preserving food stuffs in a refrigerating chamber.

Where the refrigerating chamber is of a large size, as in refrigerators for markets and the like, the cooling of this chamber and the cooling of a freezing chamber cannot ordinarily be satisfactorily accomplished with a single evaporator system on account of insufficiency of surface properly located in the cabinet for obtainin proper circulation of the air within the re rigerating chamber. The use of two evaporators or a twotemperature evaporator has been resorted to in such installations.

In refrigerator installations employing a refrigerating system of the ordinary absorption type, the two temperatures are obtained by causing the refrigerant to evaporate in two different chambers at different pressures. In refrigerator installations employing a refrigerating system of the equalized pressure obsorption type the two temperatures are obtained by causing the refrigerant to evaporate in two different chambers or evaporators, the first chamber receiving the refrigerant from the condenser and the inert gas weak in refrigerant, and the second chamber receiving the inert gas saturated atthe low temperature of the first chamber together with the overflowing refrigerant from the first chamber. This is satisfactory for units of small size, but in large installations in order to obtain better circulation in the cabinet it is desirable to extend the cooling effect over a greater area. To accomplish this an extended surface evaporator is desirable, but this type of evaporator is not adapted for use with absorption refrigerating apparatus containing pressure equalizing gas, except through the medium of a secondary system.

This secondary system operates through the boiling or vaporization of a secondary fluid by heat received from the refrigerating chamber and the condensation of such secondary fluid to give up the heat thus acquired to the evaporator. In order. that circulation may be obtained in this secondary system the secondary evaporator must ordinarily be below the primary evaporator and therefore it is desirable that the primary evaporator be near the top of the cabinet in order to keep the secondary evaporator well up in the refrigerating chamber so that it will properly cool the refrigeriting chamber. Among theobjects of the present invention is to provide a two-temperature evaporator for use in an absorption refrigerating system of the continuous type in which circulates a pressure equalizing gas, which evaporator has an extended cooling surface near or at the top of the refrigerator cabinet and a low temperature chamber for substances to be frozen.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein Fig. 1 shows, partly in vertical section, a horizontal primary evaporator and two secondary evaporators contemplated by this invention;

Fig. 2 is a view of the evaporator shown in Fig. 1 with radiating fins on the primary evaporator replacing the high temperature secondary evaporator;

Fig. 3 illustrates this invention applied to a vertical type primary evaporator; and

Fig. 4 is a sectional view taken on line H in Fig. 1.

As shown in Figs. 1 and 4 of the drawing, the primary evaporator may be formed by a horizontal fluid tight cylindrical casing 10 within which are secured horizontal baflic plates 11. Liquid refrigerant, such as ammonia, enters the evaporator through conduit 12 at the same point that the auxiliary gas, such as hydrogen, enters the evaporator through conduit 13, and for convenience conduit 12 may open into the evaporator con-v centrically within conduit 13 as shown. The

liquid ammonia flows over the baflie plates 11 toward the bottom following the courts, restricted by the baffle plates, back and forth the length of the evaporator. Heat is absorbed from the surrounding medium to evaporate the ammonia which diffuses into the equalizing gas and the resulting gas mix ture leaves the evaporator through conduit 14.

Due to the difference in the partial pressure of the equalizing gas in the upper and lower parts of the evaporator the temperature of the evaporating ammonia will be lowest on the bafile plates in the upper part of the evaporator and highest on the baflle plates in the lower part of the evaporator which are in thermal contact with the casing 10 which is thus refrigerated by the evaporation of ammonia into the enriched equalizing gas in i the bottom of the evaporator.

In order to take advantage of the difference in temperatures on the bafiie plates in the upper part of the evaporator and the casing of the evaporator, a reentrant tube 15 extends within the evaporator and is secured in good thermal relation with and supports the baffie plates in the upper part of the evaporator out of thermal contact with the casing 10. A secondary evaporator 16 containing a secondary refrigerant which may be ammonia is connected to the reentrant tube 15.

The secondary evaporator 16 is adapted to receive substances to be frozen in chamber 16a. The secondary liquid ammonia absorbs heat from the substances to be frozen and evaporates into the tube 15 where the secondary ammonia vapor is cooled and condensed by heat exchange with the evaporating refrigerant in the upper part of the primary evaporator.

Another secondary evaporator 17 having an extended radiating surface formed by fins 18 contains a secondary refrigerant such as ammonia and is connected by a conduit 19 or directly to a jacket 20 around the casing 10 of the primary evaporator. Heat is absorbed from the surrounding medium to evaporate the liquid ammonia in the secondary evaporator 17 and the vapor is condensed in jacket 20 by heat exchange with the evaporating refrigerant in the lower part of the primary evaporator.

The temperatures of the secondary evaporators 16 and 17 depend upon the pressures therein, and the pressures are determined by the cooling of the respective secondary refrigerants by the primary evaporator. Since the refrigerating effect on the ballie plates in the upper part of the primary evaporator is at a lower temperature than that on the casing 10 of the primary evaporator, the temperature of the secondary refrigerant in evaporator 16 will be lower than the temperature of the secondary refrigerant 1n the evaporator 17. The difi'erence in temperature, of course, will be dependent upon the relative loads on the respective secondary evaporators, for instance, a small load on the secondary evaporator 16 and a large load on secondary evaporator 17 means a large temperature difference and practically no load on secondary evaporator 17 means a small temrator through conduits 24 and 25 respectively. Bafie plates 26in the upper part of the evaporator are attached to the reentrant tube 23 and baflie plates in the lower part of the evaporator may be attached to the casing 22 as shown. Liquid refrigerant evaporates into the pressure equalizing gas and the resulting gas mixture leaves the evaporator through conduit 27.

As described in connection with the horizontal type of evaporator shown in Fig. 1, the

temperature of the reentrant tube 23 will belower than that of the casing 22 due to the difference in partial pressure of the auxiliary gas around the evaporating refrigerant in contact with thosev respective parts. A low temperature secondary evaporator 28 is provided which is connected directly to the reentrant tube 23 or to a fluid tight cylinder 29 located in good thermal relation with the reentrant tube 23 as shown. Cooling of the refrigerator cabinet may be accomplished either by providing fins 30 on the primary evaporator casing 22 or an extended surface secondary evaporator connected to cooling jacket around the casing 22 in the same man ner as set forth in connection with the de-- scription of the secondary evaporator shown in Fig. l. i

It will be obvious to those skilled'in the art that various other changes may be made in the construction and arrangement without departing from the spirit of the invention and therefore the invention is not limited to what is shown in the drawing and described In the specification but only as indicated in the appended claims.

I claim:

1. A coolin element comprising a vertical fluid-tight tu ular casing, a liquid refrigerant and inert gas connection to the upper portion of said casing, an outlet connection from the lower ortion of said casing, reentrant tube scale at 'its inner end and extendmg upwardly within said casing from the bottom thereof, means for defining a fluid path between said inlet and outlet connections, a portion of said path being in thermal relation with said reentrant tube, and a secondary cooling system having its condensing element in thermal relation with said reentrant tube.

2. A. cooling element comprising a horizontal fluid-tight tubular casing, a liquid refrigerant and inert gas-connection to the upper portion of said casing, an outlet connection from the lower portion of said casing, a reentrant tube sealed at its inner end and extending within said casing from one end thereof, means for defining a fluid path between said inlet and outlet connections, a portion of said path being in thermal relation with said reentrant tube, and a secondary cooling system having its condensing element in thermal relation with said reentrant tube.

3. A cooling element comprising a vertical fluid-tight tubular casing, a liquid refrigerant and inert gas connection to the upper portion of said casing, an outlet connection from the lower portion of said casing, a reentrant tube sealed at its inner end and ex tending upwardly within said casing from the bottom thereof, baliie plates for defining a fluid path between said inlet and outlet connections, some of said battle plates being in thermal relation only with said reentrant tube, and a secondary cooling system having its condensing element in thermal relation with said reentrant tube.

4-. A cooling element comprising a horizontal fluid-tight tubular casing, a liquid refrigerant and inert gas connection to the upper portion of said casing, an outlet connection from the lower portion of said casing, a reentranttube sealed at its inner end and extending within said casing from one end thereof, baflie plates for defining a fluid path between said inlet and outlet connections, some of said battle plates being in thermal relation only with said reentrant tube, and a secondary cooling system having its con- (lensing element in thermal relation with said reentrant tube.

5. A cooling element comprising a casing enclosin an evaporating chamber, connections for the circulation of gas through said chamber, an inlet for cooling liquid, two sub stantially thermally independent liquid spreading members in chamber arranged to receive liquid from said inlet and located serially with respect to the gas circulation, and independent means for transmitting heat from without said casing to each of said members.

6. A cooling element comprising a casing enclosing an evaporating chamber, connections for circulation of gas through said chamber, an inlet for cooling liquid, two substantially thermally independent groups of liquid spreading'bafile plates in said chamber arranged to receive liquid from said in- P let and grouped serially with respect to the gas circulation, and independent means for transmitting heat from without said casing to each of said groups.

7 A cooling element comprising a casing enclosing an evaporating chamber, connections for circulation of. gas through said chamber, an inlet for cooling liquid, two substantially thermally independent groups of liquid spreading baflie plates in said chamber arranged to receive liquid from said inlet and grouped serially with respect to the gas circulation, and means utilizing a secondary heat conducting fluid for transmitting heat from without said casing to one of said members.

8. A. cooling element comprising a casing provided with exterior heat radiating fins and enclosing an evaporating chamber, connections for the circulation of gas therethrough, an inlet for cooling liquid, a first group of liquid spreading baiiies in said chamber attached to said casing, a second group of battles substantially thermally.independent of the first, said groups being arranged in series with respect to the gas circulation, and means utilizing a secondary cooling fluid for conductingheat from without said casing to said second group of battles.

9. A cooling element comprising a casing enclosing an evaporating chamber, connections for the circulation of gas therethrough, an inlet for cooling liquid, a secondary condensing-evaporating system with the condensing portion extending through said casing into said chamber, and two liquid spreading members in said chamber arranged to receive liquid from said inlet and located serially with respect to the gas circulation, one of said members being attached to said casing and the other in thermal conductive relation to said condensing portion.

10. A cooling element comprising'a horizontally elongated casing enclosing an evaporating chamber, connections for the circulation of gas therethrough, an inlet for cooling liquid, a secondary condensing-evaporating system with the condensing portion extending through said easing into said chamber, and two groups of liquid spreading battles in said chamber grouped serially with respect to the gas circulation, one of said groups being attached to said casing and the other to said condensing portion.

11.- it cooling element comprising a horizontally elongated casing enclosing an evap crating chamber, connections for the circulation of gas therethrough, an inlet for cooling liquid, a secondary cooling system with the heat rejecting portion thereof extending through said casing into said chamber, and two groups of liquid spreading ballles within said chamber grouped serially with respect to the gas circulation, one of said groups being attached to said casing and the other to said heat rejecting portion.

12. A cooling element comprising a vertically elongated casing enclosing an evaporating chamber, connections for the circulation of gas therethrough, an inlet for cooling liquid at the top of said chamber, a secondary condensing-evaporating system With the condensing portion extending through said casing into said chamber, and two groups of liquid spreading bafiies in said chamber grouped serially with respect to the gas circulation, one of said groups being attached to said casing and the other in thermal relation to said condensing portion.

13. A cooling element comprising a vertically elongated casing enclosing an evaporating chamber, connections for the circulation of gas therethrough, an inlet for cooling liquid in the upper part of said chamber, a secondary cooling system having its heat rejecting portion extending through the bottom of said casing upwardly into said chamber, and two groups of liquid spreading baffies in said chamber arranged to receive liquid from said inlet and grouped serially With respect to the gas circulation, one of said groups being attached to said casing and the other to said heat rejecting portion.

, In testimony whereof I afliX my signature.

ROBERT S. TAYLOR. 

